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107 lines
5.2 KiB
107 lines
5.2 KiB
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Continuing Development</title>
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<a href="index.html">
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<font color="#004faf">Home</font></a>
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<font color="#004faf">All Classes</font></a>
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<font color="#004faf">Main Classes</font></a>
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<font color="#004faf">Annotated</font></a>
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<font color="#004faf">Grouped Classes</font></a>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Continuing Development</h1>
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[ <a href="motif-walkthrough-9.html">Previous: Replacing the Print Dialog</a> ]
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[ <a href="motif-walkthrough.html">Home</a> ]
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<p> We have not quite finished with the migration to Qt, even though our
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project does not use <a href="motif-extension.html#Motif">Motif</a> any more. Qt provides many useful features
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that we can begin using immediately. Some of the most interesting
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ones are presented below as a guide for where to start extending your
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existing projects.
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<p> <h2> Using Unicode
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</h2>
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<a name="1"></a><p> Support for <a href="i18n.html">internationalization</a> is very easy
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with Qt. Using <a href="qstring.html">QString</a> instead of <tt>char*</tt> for storing text gives
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us support for most of the written languages around the world. Our <tt>Page</tt> and <tt>Options</tt> structs look much simpler now.
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<p>
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<p> <pre></pre>
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<p> <pre></pre>
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<p> All functions that use the <tt>Page</tt> and <tt>Options</tt> structs need to be
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updated to use QString properly. Since QString is also an <a href="shclass.html#implicitly-shared">implicitly shared</a> class, we no longer have to do any memory management with our
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strings. We can remove all occurences of the <a href="qcstring.html#qstrdup">qstrdup</a>() function,
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and we never need to use <em>new</em> or <em>delete</em> when done with a string.
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QString will allocate and delete data when needed.
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<p> Here are the <tt>MainWindow::fileOpen()</tt> and <tt>MainWindow::pageChange()</tt>
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functions from <tt>mainwindow.ui.h</tt>. Notice that the code no longer
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uses <em>delete</em> or <a href="qcstring.html#qstrdup">qstrdup</a>() when storing text.
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<p>
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<p> <pre></pre>
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<p> <pre>
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...
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</pre>
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<p> <pre></pre>
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<p> Almost all of the functions in our application are affected by this
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change. In most cases, we end up removing more code than we are
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adding. To keep the size of this walkthrough reasonable, we've only
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shown a small portion of the required changes, since the changes are
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very similar to those shown above.
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<p> <h2> Writing Platform-Independent Code
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</h2>
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<a name="2"></a><p> Qt provides many <a href="io.html">input and output</a> classes. We
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can use these in <tt>MainWindow::readDB()</tt> and <tt>MainWindow::saveDB()</tt>.
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Currently, these functions use functions only found on UNIX machines.
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Using <a href="qfile.html">QFile</a> and <a href="qtextstream.html">QTextStream</a> removes this dependency on UNIX, and we can
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begin building and testing our application on Microsoft Windows and
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Apple Mac OS X.
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<p> The platform-independent versions of the <tt>MainWindow::readDB()</tt> and
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<tt>MainWindow::saveDB()</tt> functions can be found in the <tt>io.cpp</tt> file.
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<p> <h2> Designing a Modern User Interface
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</h2>
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<a name="3"></a><p> Since we used the <em>Qt Designer</em> to design the <em>Main Window</em>
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widget, we can extend the interface easily. We can use some of the
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more advanced features of <a href="qmainwindow.html">QMainWindow</a>, which includes dockable
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toolbars. Adding these is simple with the <em>Qt Designer</em>. The
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final version of our project includes a toolbar, which provides quick
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access to the <em>Open</em>, <em>Save</em>, <em>Print</em>, <em>New Page</em> and <em>Delete to Trash</em> actions.
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<p> The possibilities are endless. An <em>Edit</em> menu, with the common <em>Cut</em>, <em>Copy</em> and <em>Paste</em> actions, could be added in a relatively
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short period of time. As our project expands to other platforms, we
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could add menus and dialogs that allow us synchronize todo lists
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between a normal desktop computer and a handheld device running with
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Qt/Embedded.
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<p> [ <a href="motif-walkthrough-9.html">Previous: Replacing the Print Dialog</a> ]
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[ <a href="motif-walkthrough.html">Home</a> ]
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<p>
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<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>Qt 3.3.8</div>
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</table></div></address></body>
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